Angular momentum generation in nuclear fission.

When a heavy atomic nucleus splits (fission), the resulting fragments are observed to emerge spinning1; this phenomenon has been a mystery in nuclear physics for over 40 years2,3. The internal generation of typically six or seven units of angular momentum in each fragment is particularly puzzling for systems that start with zero, or almost zero, spin. There are currently no experimental observations that enable decisive discrimination between the many competing theories for the mechanism that generates the angular momentum4-12. Nevertheless, the consensus is that excitation of collective vibrational modes generates the intrinsic spin before the nucleus splits (pre-scission). Here we show that there is no significant correlation between the spins of the fragment partners, which leads us to conclude that angular momentum in fission is actually generated after the nucleus splits (post-scission). We present comprehensive data showing that the average spin is strongly mass-dependent, varying in saw-tooth distributions. We observe no notable dependence of fragment spin on the mass or charge of the partner nucleus, confirming the uncorrelated post-scission nature of the spin mechanism. To explain these observations, we propose that the collective motion of nucleons in the ruptured neck of the fissioning system generates two independent torques, analogous to the snapping of an elastic band. A parameterization based on occupation of angular momentum states according to statistical theory describes the full range of experimental data well. This insight into the role of spin in nuclear fission is not only important for the fundamental understanding and theoretical description of fission, but also has consequences for the γ-ray heating problem in nuclear reactors13,14, for the study of the structure of neutron-rich isotopes15,16, and for the synthesis and stability of super-heavy elements17,18.

Anomalies in the Charge Yields of Fission Fragments from the

Fast-neutron-induced fission of ^{238}U at an energy just above the fission threshold is studied with a novel technique which involves the coupling of a high-efficiency γ-ray spectrometer (MINIBALL) to an inverse-kinematics neutron source (LICORNE) to extract charge yields of fission fragments via γ-γ coincidence spectroscopy. Experimental data and fission models are compared and found to be in reasonable agreement for many nuclei; however, significant discrepancies of up to 600% are observed, particularly for isotopes of Sn and Mo. This indicates that these models significantly overestimate the standard 1 fission mode and suggests that spherical shell effects in the nascent fission fragments are less important for low-energy fast-neutron-induced fission than for thermal neutron-induced fission. This has consequences for understanding and modeling the fission process, for experimental nuclear structure studies of the most neutron-rich nuclei, for future energy applications (e.g., Generation IV reactors which use fast-neutron spectra), and for the reactor antineutrino anomaly.

Dental enamel defects in German medieval and early-modern-age populations.

SUMMARY: Aim of this study was to investigate the frequency and type of developmental defects of enamel (DDE) in a medieval and an early-modern-age population from Thuringia, Germany. Sixty-six skeletons subdivided into 31 single burials (12th/13th c.) and 35 individuals buried in groups (15th/16th c.) were examined. DDE were classified on 1,246 teeth according to the DDE index. Molar-incisor-hypomineralisation (MIH), a special type of DDE, was recorded according to the European Academy of Paediatric Dentistry (EAPD) criteria. DDE was found in 89.4% of the individuals (single burials 90.3% and group burials 88.6%). Hypoplastic pits were the most frequent defect in primary teeth and linear enamel hypoplasia (LEH) in permanent teeth. 13 individuals (24.1%) showed at least one hypomineralised permanent tooth, 12.2% had MIH on at least one first permanent molar and 10.0% in permanent incisors. Second primary molars were affected in 8.0% of the children and juveniles. No individual suffered from affected molars and incisors in combination. Endogenous factors like nutritional deficiencies and health problems in early childhood could have been aetiological reasons of DDE and MIH. The frequency of DDE and MIH might have been masked by extended carious lesions, dental wear and ante-mortem tooth loss.

[Current Guidelines to Prevent Obesity in Childhood and Adolescence]. / Aktuelle Empfehlungen zur Prävention der Adipositas im Kindes- und Jugendalter.

BACKGROUND: Current guidelines for the prevention of obesity in childhood and adolescence are presented. METHODS: A literature search was performed in Medline via PubMed, and appropriate studies were analysed. RESULTS: Programs to prevent childhood obesity were to date mainly school-based. Effects were limited to date. Analyses tailored to different age groups show that prevention programs have the best effects in younger children (< 12 years). Evidence based recommendations for preschool- and early school age imply the need for interventions addressing parents and teachers alike. During adolescence, school-based interventions were most effective when adolescents were directly addressed. To date, obesity prevention programs have mainly focused on behavior oriented prevention. Recommendations for condition oriented prevention have been suggested by the German Alliance of Non-communicable Diseases and include one hour of physical activity at school, promotion of healthy food choices by taxing unhealthy foods, mandatory quality standards for meals at kindergarten and schools as well as a ban on unhealthy food advertisement addressing children. CONCLUSION: Behavior oriented prevention programs showed hardly any or only limited effects in the long term. Certain risk groups for the development of obesity are not reached effectively by available programs. Due to the heterogeneity of available studies, universally valid conclusions cannot be drawn. The combination with condition oriented prevention, which has to counteract on an obesogenic environment, is crucial for sustainable success of future obesity prevention programs.

Decay and Fission Hindrance of Two- and Four-Quasiparticle K Isomers in

Two isomers decaying by electromagnetic transitions with half-lives of 4.7(1.1) and 247(73) µs have been discovered in the heavy ^{254}Rf nucleus. The observation of the shorter-lived isomer was made possible by a novel application of a digital data acquisition system. The isomers were interpreted as the K^{π}=8^{-}, ν^{2}(7/2^{+}[624],9/2^{-}[734]) two-quasineutron and the K^{π}=16^{+}, 8^{-}ν^{2}(7/2^{+}[624],9/2^{-}[734])⊗8^{-}π^{2}(7/2^{-}[514],9/2^{+}[624]) four-quasiparticle configurations, respectively. Surprisingly, the lifetime of the two-quasiparticle isomer is more than 4 orders of magnitude shorter than what has been observed for analogous isomers in the lighter N=150 isotones. The four-quasiparticle isomer is longer lived than the ^{254}Rf ground state that decays exclusively by spontaneous fission with a half-life of 23.2(1.1) µs. The absence of sizable fission branches from either of the isomers implies unprecedented fission hindrance relative to the ground state.

Introducing excess body weight in childhood and adolescence and comparison with body mass index and waist-to-height ratio.

BACKGROUND: Weight status in children and adolescents is commonly defined using age- and gender-corrected standard deviation scores for body mass index (BMI-SDS, also called z-scores). Values are not reliable for the extremely obese however. Moreover, paediatricians and parents may have difficulties understanding z-scores, and while percentiles are easier to gauge, the very obese have values above the 99th percentile, making distinction difficult. The notion of excess body weight (EBW) is increasingly applied in adult patients, mainly in the context of bariatric surgery. However, a clear definition is not available to date for the paediatric population. METHODS: A simple definition of EBW for children and adolescents is introduced, with median weight as a function of height, age and gender (characterized by an asterisk): EBW (%) = 100x(weight-median weight*)/median weight*. EBW is compared with BMI-SDS and waist-to-height ratio (WHtR). Using two data sources (APV registry and German Health Interview and Examination Survey for Children and Adolescents (KiGGS)) including more than 14,000 children, the relationships between these anthropometric and various metabolic parameters are analysed for a group of overweight/obese children who have sought obesity therapy (APV), for the general paediatric population and for the subset of overweight/obese children from the general population (KiGGS). RESULTS: The three anthropometric parameters are strongly correlated, with the linear correlation coefficients exceeding 0.8 in the general population and 0.75 in those seeking obesity therapy. Moreover, their relationship to metabolic parameters is quite similar regarding correlations and area under the curve from receiver operating characteristic analyses. CONCLUSIONS: EBW has similar predictive value for metabolic or cardiovascular comorbidities compared with BMI and WHtR. As it is reliable at the extreme end of the obesity spectrum, easily communicable and simple to use in daily practice, it would make a very useful addition to existing tools for working with obese children and adolescents. Its usefulness in assessing weight change needs to be studied however.

Fission barrier of superheavy nuclei and persistence of shell effects at high spin: cases of 254No and 220Th.

We report on the first measurement of the fission barrier height in a heavy shell-stabilized nucleus. The fission barrier height of 254No is measured to be Bf=6.0±0.5 MeV at spin 15ℏ and, by extrapolation, Bf=6.6±0.9 MeV at spin 0ℏ. This information is deduced from the measured distribution of entry points in the excitation energy versus spin plane. The same measurement is performed for 220Th and only a lower limit of the fission barrier height can be determined: Bf(I)>8 MeV. Comparisons with theoretical fission barriers test theories that predict properties of superheavy elements.

Adiposity rebound is misclassified by BMI rebound.

BACKGROUND/OBJECTIVES: Adiposity rebound (AR) is defined as the nadir or the inflexion point of body mass index (BMI) percentiles between the age of 3 and 7 years. An early rebound is seen as a risk of obesity and, thus, AR is considered as a suitable time period for prevention. As BMI does not reflect body composition, we aimed to examine the rebounds of fat mass index (FMI) and fat-free mass index (FFMI) together with BMI. SUBJECTS/METHODS: Cross-sectional data of 19 264 children aged 3-11 years were pooled from three German studies (Kiel Obesity Prevention Study, the project 'Better diet. More exercise. KINDERLEICHT-REGIONS' and regular examinations of Jena children). Height and weight were measured. Fat mass (FM) and fat-free mass (FFM) were obtained from bioelectrical impedance analysis and analysed using a population-specific algorithm. Percentiles of BMI, FMI and FFMI were constructed by the LMS method. RESULTS: Both BMI and FMI percentiles showed a rebound, whereas FFMI percentiles steadily increased with age. On P90, FMI rebound was about 1.6-1.8 years later compared with that of BMI, that is, at ages 4.2 years (BMI) and 5.8 years (FMI) in boys and at 4.2 years (BMI) and 6.0 years (FMI) in girls. At AR, the slope of the BMI-P90 was explained by increases in FFMI rather than FMI. By contrast, at FMI rebound, the slope of BMI was strongly related to FMI. CONCLUSIONS: BMI rebound does not equal the rebound of FM. At AR, the slope in BMI is determined by the increase in FFMI. AR should be defined as FMI rebound rather than BMI rebound.

"Obese equals lazy?" analysis of the association between weight status and physical activity in children.

INTRODUCTION: Literature provides evidence that overweight children are more sedentary. To verify this generalized statement behavior patterns of overweight and nonoverweight children needs to be understood. Therefore, we investigated the distribution of sedentary and activity levels in a quantitative and qualitative way. METHODS: Data was collected from 37 randomly selected nonoverweight and 55 overweight children. They were 8 to 11 years of age. Height and weight were measured and weight status was characterized by BMI (BMI-percentile, BMI-SDS). Daily PA (physical activity) was measured by direct accelerometry. Spare time and screen time entertainment were obtained by questionnaires. RESULTS: The amount of time spent "passive" was significantly higher in overweight children, while nonoverweight children were more "active." The multiple regression model shows a significant association between weight status (BMI-SDS) and activity parameters. Additionally, screen time entertainment was significantly related to BMI-SDS. CONCLUSION: The results support the statement that overweight children are less active than nonoverweight children. The high amount of PA seems to be an important factor to prevent overweight in children given that PA shows the highest correlation to weight status. Quantitative and qualitative measurements are needed for further analysis.

Shell-structure and pairing interaction in superheavy nuclei: rotational properties of the z=104 nucleus (256)rf.

The rotational band structure of the Z=104 nucleus (256)Rf has been observed up to a tentative spin of 20ℏ using state-of-the-art γ-ray spectroscopic techniques. This represents the first such measurement in a superheavy nucleus whose stability is entirely derived from the shell-correction energy. The observed rotational properties are compared to those of neighboring nuclei and it is shown that the kinematic and dynamic moments of inertia are sensitive to the underlying single-particle shell structure and the specific location of high-j orbitals. The moments of inertia therefore provide a sensitive test of shell structure and pairing in superheavy nuclei which is essential to ensure the validity of contemporary nuclear models in this mass region. The data obtained show that there is no deformed shell gap at Z=104, which is predicted in a number of current self-consistent mean-field models.

Percentile curves for skinfold thickness in 7- to 14-year-old children and adolescents from Jena, Germany.

OBJECTIVE: To present age- and sex-specific percentile curves for triceps and subscapular skinfold thickness, and to investigate long-term changes in skinfold thickness in children. SUBJECTS/METHODS: A cross-sectional study of children and adolescents was conducted in Jena/Germany in 2005/2006. The sample consisted of 2132 children (1018 girls and 1114 boys) aged 7-14 years and equated to the anthropometric characteristics of the German sample included in the reference values for body mass index (BMI). Height, weight and triceps and subscapular skinfold measurements were obtained using standardized methods. Smoothed percentile curves for triceps and subscapular skinfold thickness were derived by the LMS method. Data were compared with historical data of Jena schoolchildren from 1975. RESULTS: In both sexes, skinfold thickness increased between 7 and 14 years of age in a sex-specific pattern, with generally higher median values for triceps and subscapular skinfold in girls than boys. A comparison with skinfold thickness measured in Jena schoolchildren three decades ago showed a significant increase in subcutaneous fat. The changes in the lower range (below the tenth percentile) of the distribution exceed those in the upper range (above the 90th percentile) for both triceps and subscapular skinfold in both sexes. Furthermore, this gain in subcutaneous fat mainly occurred in underweight and normal-weight subjects, whereas skinfold thickness remained nearly unchanged in overweight subjects. CONCLUSIONS: The up-to-date percentile curves for skinfold thickness provide a basis for monitoring of individuals and evaluation of long-term trends in German children and adolescents. The changes in skinfold thickness indicate an unfavourable increase in adiposity, as well as an unfavourable change in the relationship between BMI and body fat in children and adolescents over time.

Comparison of gamma-ray coincidence and low-background gamma-ray singles spectrometry.

Aerosol samples have been studied under different background conditions using gamma-ray coincidence and low-background gamma-ray singles spectrometric techniques with High-Purity Germanium detectors. Conventional low-background gamma-ray singles counting is a competitive technique when compared to the gamma-gamma coincidence approach in elevated background conditions. However, measurement of gamma-gamma coincidences can clearly make the identification of different nuclides more reliable and efficient than using singles spectrometry alone. The optimum solution would be a low-background counting station capable of both singles and gamma-gamma coincidence spectrometry.

[Certification of therapy institutions, obesity trainers, and obesity trainer academies by the German Working Group on Obesity in Children and Adolescents (AGA)]. / Was hat die Arbeitsgemeinschaft Adipositas im Kindes- und Jugendalter durch die Zertifizierung von Behandlungseinrichtungen, Adipositas-Trainern und Adipositas-Trainer-Akademien erreicht?

There is a vast choice of behavioral therapy for obesity in children and adolescents, with wide differences in quality. In order to provide orientation for families, physicians, and health insurance companies, the German Working Group on Obesity in Children and Adolescents (AGA), which is affiliated with the German Obesity Society (DAG) and the German Pediatric Society (DGKJ), offers to certify institutions providing patient education programs for obese children and adolescents, obesity trainers, and academies for obesity trainers. Currently, 60 institutions offer obesity care, while 81 obesity trainers and 8 trainer academies are certified. This article summarizes requirements for certification and preliminary experience.

Validity of body mass index and waist circumference to detect excess fat mass in children aged 7-14 years.

BACKGROUND/OBJECTIVES: To evaluate the screening performance of body mass index (BMI) and waist circumference (WC) for excess adiposity. In addition, the diagnostic accuracy of cutoffs from different international and national reference systems based on BMI and WC was investigated. SUBJECTS/METHODS: Data from 2132 Jena children aged 7-14 years conducted in 2005/2006 were analyzed. Receiver operating characteristic (ROC) curves were constructed to assess BMI and WC, as screening measures for excess adiposity (derived from skinfolds). Sensitivity, specificity and positive predictive values (PPVs) were calculated for two BMI-based classification systems (IOTF and German reference) and sample-based WC cutoffs. RESULTS: The BMI as well as the WC performed well in detecting excess fat mass, indicated by areas under the ROC curve (AUC) close to 1.0, with slightly greater AUCs for BMI than for WC in both sexes. The specificity of all reference systems was high for both sexes (95 to 98%). However, their sensitivities were low (53-67% in boys; 51-67% in girls). PPV were higher for the German reference and the sample-based WC cutoffs than for the IOTF reference, and higher in girls than in boys. CONCLUSIONS: The setting in which the reference system should be used is important for the selection of the reference system. The results support the use of the BMI-based references for monitoring in epidemiological studies. The sample-based cutoffs for WC should be refined for clinical use on national level.

Gamma-ray spectroscopy at the limits: first observation of rotational bands in 255Lr.

The rotational band structure of 255Lr has been investigated using advanced in-beam gamma-ray spectroscopic techniques. To date, 255Lr is the heaviest nucleus to be studied in this manner. One rotational band has been unambiguously observed and strong evidence for a second rotational structure was found. The structures are tentatively assigned to be based on the 1/2-[521] and 7/2-[514] Nilsson states, consistent with assignments from recently obtained alpha decay data. The experimental rotational band dynamic moment of inertia is used to test self-consistent mean-field calculations using the Skyrme SLy4 interaction and a density-dependent pairing force.

A longitudinal study of autism spectrum disorders in individuals diagnosed with a developmental language disorder as children.

BACKGROUND: A number of studies have shown that the diagnosis of developmental language disorder (DLD) can be unstable over time, such that young children with a diagnosis of DLD may show symptoms more characteristics of autism spectrum disorder (ASD) at a later date. METHOD: To estimate the types and prevalence of ASD 469 individuals with a DLD, consecutively assessed in the same clinic during a period of 10 years, and 2345 controls from the general population were screened for ASD through the nationwide Danish Psychiatric Central Register (DPCR). The mean length of observation was 34.7 years, and the mean age at follow-up 35.8 (range: 28.3-46.7) years. RESULTS: At follow-up, 10 (2.1%) in the DLD group and two (0.09%) in the comparison group were known in the DPCR with a diagnosis of any ASD (P < 0.0001; odds ratio = 25.5; 95% confidence interval 5.5-116.9). CONCLUSION: Our results provide additional support to the notion that DLD is a marker of increased vulnerability to the development of ASD.

Epidermal growth factor receptor kinase domain mutations are rare in salivary gland carcinomas.

Activating mutations within the epidermal growth factor (EGFR) tyrosine kinase domain identify non-small cell lung cancer patients with improved clinical response to tyrosine kinase inhibitor therapy. Recently, we identified two EGFR mutations in a cohort of 25 salivary gland carcinomas (SGCs) by screening the tumour samples for the both most common hotspot mutations in exons 19 and 21 by allele-specific PCR. Here, we present a comprehensive sequencing analysis of the entire critical EGFR tyrosine kinase domain in 65 SGC of the main histopathological types. We found EGFR mutations in the tyrosine kinase domain to be a rare event in SGCs. No additional mutations other than the two known exon 19 deletions (c.2235_2249del15) in a mucoepidermoid carcinoma and an adenoid cystic carcinoma have been detected. Other putative predictive markers for EGFR-targeted therapy in SGCs might be relevant and should be investigated.

The psychosocial situation of obese children: Psychological factors and quality of life.

The psychosocial situation of obese children at the beginning of the Freiburg Intervention Trial for Obese Children (FITOC) program influences the course and outcome of intervention therapy. At the beginning of FITOC, mothers of 30 children (12 ♂ age 10.5 ± 1.4, 18 ♀; 10.2 ± 1.3) rated the psychopathological symptoms using the Child Behavior Checklist (CBCL) and the quality of life of their children (Inventar zur Erfassung der Lebensqualität [ILK]). 46.6% of mothers rated their children to be disturbed (normal population group, 2% disturbed). There was no correlation between the body mass index of the child and the CBCL score. On the ILK, the obese children themselves selected "good" while the mother's view of their childrens' quality of life varied around "poor". The stress on the mother increased with the degree of the child's obesity and number of critical life events (p = 0.030). The CBCL and the ILK at the beginning of treatment serve as a good screening instrument for psychopathology and distress in children with obesity.

The role of taste and appetite regulation in the understanding of overweight and obesity. Proceedings of the 16th Aschauer Soiree, 26th April 2008.

Overweight and obesity have developed into major illnesses in most Western societies and significantly contribute to the financial burden of modern public health systems. Almost daily, new therapeutic proposals are published in the lay press, and also the scientific literature has increased dramatically in recent years. E.g., when searching MEDLINE (1966 - May 2008 (1)), the key word "obesity" meanwhile appears in more than 108,000 articles. Primary focus however, is put upon aspects of treatment, neglecting the role of taste and appetite regulation. Combining keywords like "obesity + treatment" results in over 50.000 citations, "obesity + diet" in over 23.000, "obesity + energy + expenditure" in over 13.000 citations (even "obesity + gastric + bypass" still evoke 2.600 citations), whereas "obesity + appetite + regulation" result in some 3.000, "obesity + NPY" - neuropeptid Y being one of the major chemical stimulators of appetite - evoke some 500 and "obesity + Arc + nucleus" - the arcuate nucleus being the anatomical centre of appetite regulation - no more than 370 scientific publications. The apparent scarcity of literature about taste and appetite regulation and the amazing lack of interest in neuronal information processing in overweight and obesity, has prompted the authors to brainstorm new aspects of the world-wide derailment of weight control.